Question: Expand.
We expand the parentheses using the distributive property : $ A(B+C+D)= A\cdot B+ A\cdot C+ A\cdot D$ We can also think about the problem using an area model: $-h^2$ $2h$ $-1$ $3h$ Here's how the solution goes, algebraically: $\begin{aligned} &\phantom{=}{3h}(-h^2+2h-1) \\\\ &={3h}(-h^2)+{3h}(2h)+{3h}(-1) \\\\ &=-3h^3+6h^2-3h \end{aligned}$ Here's how the solution looks in terms of the area model: $-3h^3$ $6h^2$ $-3h$ $-h^2$ $2h$ $-1$ $3h$ In conclusion, $3h(-h^2+2h-1)=-3h^3+6h^2-3h$